Chapter 4 Making Measurements 115
to assert SRQ (RQS command). The EXTOUT SRQ pulse does not
necessarily occur whenever the SRQ bit is set; it occurs whenever an
enabled status event occurs.
The following program uses the SRQ event to synchronize the multimeter to
external equipment. The program downloads a subprogram to the
multimeter. When the subprogram is called by the controller (line 120), it
configures the multimeter for high-accuracy temperature measurements
using a 10k(W) thermistor. After the subprogram has been called and
executed, bit 0 is set in the status register (program memory execution
completed). This asserts a GPIB SRQ (enabled by line 30) and causes a pulse
on the Ext Out connector (specified by line 40). This pulse signals external
equipment that the multimeter is configured and ready to make
measurements.
10 OUTPUT 722;"SUB EXTSRQ" ! STORE SUBPROGRAM NAMED "EXTSRQ"
20 OUTPUT 722;-"PRESET NORM" ! PRESET,TRIG SYN, TARM AUTO, NRDGS 1,AUTO
30 OUTPUT 722;"RQS 1" !ENABLE SUBPROGRAM EXECUTION COMPLETE BIT
40 OUTPUT 722;"EXTOUT SRQ,POS" !SRQ EXTOUT EVENT, HI-GOING PULSE
50 OUTPUT 722;"OHMF 10E3" !2-WIRE OHMS, 10k
W RANGE
60 OUTPUT 722;"NPLC 100" !100 PLCS INTEGRATION TIME
70 OUTPUT 722;"OCOMP ON" !ENABLE OFFSET COMPENSATION
80 OUTPUT 722;"TRIG EXT" !EXTERNAL TRIGGER EVENT
90 OUTPUT 722;"MATH CTHRM10K" !ENABLE 10k
W THERMISTOR MATH OPERATION
100 OUTPUT 722;"CSB" !CLEAR STATUS REGISTER
110 OUTPUT 722;"SUBEND" !END OF SUBPROGRAM
120 OUTPUT 722;"CALL EXTSRQ" !CALL SUBPROGRAM
130 END
EXTOUT ONCE Executing the EXTOUT ONCE command produces a single 1µS pulse on
the multimeter's Ext Out connector. After executing EXTOUT ONCE, the
mode reverts to OFF (the EXTOUT signal is disabled). As shown in the
following program. EXTOUT ONCE is useful in subprograms to indicate
the completion of the subprogram, or a segment of the subprogram, to
external equipment.
10 OUTPUT 722;"SUB EXTONCE" !STORE SUBPROGRAM NAMED "EXTONCE"
20 OUTPUT 722;"EXTOUT ONCE" !SIGNAL EXTERNAL EQUIPMENT TO SWITCH
25 !TO DC VOLTAGE SIGNAL
30 OUTPUT 722;"PRESET FAST !FAST READINGS, TARM SYN, TRIG AUTO"
40 OUTPUT 722;"MEM FIFO" !ENABLE READING MEMORY, FIFO MODE
50 OUTPUT 722;"NRDGS 20" !20 READINGS PER TRIGGER
60 OUTPUT 722;"TARM SGL" !TRIGGER 20 READINGS
70 OUTPUT 722;"EXTOUT ONCE" !SIGNAL EXTERNAL EQUIPMENT TO SWITCH TO
75 !RESISTANCE MEASUREMENT
80 OUTPUT 722;"OCOMP ON" !ENABLE OFFSET COMPENSATION
90 OUTPUT 722;"OHM 1E3" !2-WIRE OHMS, 1K
W RANGE
100 OUTPUT 722;"NRDGS 40" !40 READINGS PER TRIGGER
110 OUTPUT 722;"TARM SGL !TRIGGER 40 READINGS"
120 OUTPUT 722;"SUBEND" !END OF SUBPROGRAM
130 OUTPUT 722;"CALL EXTONCE" !CALL SUBPROGRAM
140END
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